Quick-make,quick-break actuator for high voltage electrical contacts



E. J. KOTS Nov. 24, 1970 Kl CTUAT OR FOR HIGH ACTS T N O C AL KA AC EI Rm BC QUICK-MAKE, QUICK- VOLTAGE ELE Filed Feb.l 2s 1968 2 Sheets-Sheet l NNNN.

E. J. KOTS FOR HIGH TS 2 Sheets-Sheet 2 Filed Feb. 23, 1968 l iztflww 55,4 l I l l Q.

United States Patent O 3,542,986 QUICK-MAKE, QUICK-BREAK ACTUATOR FOR HIGH VOLTAGE ELECTRICAL CONTACTS Edward J. Kotski, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Filed Feb. 23, 1968, Ser. No. 707,779 Int. Cl. H01h 33/70, 33/76 U.S. Cl. 200-149 15 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to apparatus for rapidly moving high voltage electrical contacts, and particularly, to a gas-actuated contact moving assembly adapted for use with high voltage contacts that normally are situated in confined spaces where the generation of gases by contact arcing is highly undesirable. More specifically, the invention is ideally suited for use with high voltage electrical conductor terminations of the type utilized in underground power distribution systems.

It is well known that when an energized electric circuit is opened, for example by disengagiug the relatively movable contacts of a switch in the circuit, an arc is drawn between the separated contacts of the switch. The magnitude of the arc thus formed is proportional to the amount of current and the voltage level of the circuit that is interrupted. Accordingly on high voltage power transmission systems, which conduct large currents, an arc of considerable magnitude may be formed when a circuit is opened. In addition, when open contacts in such a high voltage circuit are moved toward engagement with one another when the circuit is energized, an arc will be formed between the contacts before they actually come into engagement due to the high voltage breaking down the insulating air between the contacts. In order to reduce the amount of arcing damage sustained by contacts in those portions of high voltage circuits that must be frequently opened and closed, it is common practice to employ various types of mechanically actuated, high speed circuit interrupters, or circuit breakers, to perform the necessary contact opening or closing functions. However, there are many electric power switching applications that are so infrequently used that the use of expensive power circuit breaking or circuit interrupting devices are not warranted. Generally in such applications, a manually actuated pair of contacts are closed by an operator rapidly moving them into or out of engagement. The speed of manual operation is thus relied on to limit contact damage resulting from prolonged arcing.

Under normal operating conditions, manual operation of switching contacts in a power distribution system is a generally satisfactory practice because the arcing wear is not severe and when such contacts are exposed to the atmosphere there is little danger to the operator. However, if the contacts being manually moved into engagement or disengagement are situated in a confined space, a substantial danger exists that equipment may be excessively damaged, or an operator may be injured, with such a mode of operation. 'Ihe gases developed during the contact pre-strike, or arcing, condition may develop explosive pressures within the confined space and, thus, burst the equipment causing pieces of it to be hurdled through the surrounding area. Such a danger is heightened by the common practice employed on high voltage power distribution systems of placing gas evolving, are quencing material adjacent relatively movable contacts for the purpose of quickly extinguishing arcs formed when the contacts are separated. When such gas evolving, arc queueing materials are utilized, the magnitude and duration of the arcs formed by opening and closing the contacts under normal line current and voltage conditions does not usually develop a dangerous amount of gas, and destructive explosions do not result. However, an inherent problem in such systems is that a short circuit may be present on the system at the time a pair of relatively movable contacts are moved toward engagement with one another. Under such a short circuit condition, an abnormally high arc current would be created during the pre-strike interval prior to the engagement of the contacts and this arc would usually develop enough gas to either throw one of the contacts toward the operator, or perhaps cause an explosion of the contact assembly if the gas conning means around the contacts is not well vented.

An advantage of my invention is that it provides a mechanically simple and inexpensive contact operating means that is responsive to an arc being drawn between two relatively movable contacts to move the contacts quickly and automatically so that the duration of the arc is sharply limited and, thus, the amount of gas developed by the arc is kept at safe minimum levels. In one form of the invention, a movable contact is directly mounted on a piston that is positioned in a cylinder well on a high voltage bushing. Means are provided for electrically connecting the piston mounted contact to a high voltage conductor in the bushing and a gas confining channel is disposed between the space surrounding the contact and the interior of the cylinder well. In operation, as a second high voltage contact is moved toward engagement with the piston mounted contact, when the system is energized, an arc will be drawn between the two contacts across a gas evolving, arc quencing material. The gas thus evolved forces the piston and the contact mounted thereon to move rapidly into engagement with the second contact. An additional feature of this form of my invention resides in the fact that the piston mounted contact aiords a lost-motion mode of separating the two contacts so that when the second contact is moved away from the bushing, it is accelerated appreciably before the contacts are actually separated; therefore, the contacts are quickly snapped open to again limit the magnitude and duration of the arc formed between the contacts.

An object of my invention is to provide a gas-actuated contact moving assembly that operates solely on arc-gen erated gases so that no other prime mover is required.

Another object of the invention is to provide means for rapidly closing a pair of relatively movable contacts in response to the formation of a pre-strike arc between the contacts thereby to limit the amount of gas developed by the arc as well as to limit the extent of burning or other damage done to the contacts during the arcing portion of the contact closing cycle.

A further object of the invention is to provide automatic contact closing means for a pair of manually operable electrical contacts to remove the Contact closing operation from the control of a manual operator when an arc is formed between the contacts.

Still another object of the invention is to provide contact closing means for relatively movable contacts that are normally positioned in a relatively conned space;

the contact closing means being characterized by incorporating gas storage means that obviate the necessity of venting arc generated gas from the confined space.

Yet another object of the invention is to provide a contact closing assembly for a conductor bushing that is hermetically sealed on a liquid filled container.

A still further object of the invention is to provide a high voltage conductor termination having improved contact moving means therein which substantially improve the operating safety of the termination.

Further objects and advantages will become apparent as the description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of the specification.

In the drawings:

FIG. 1 is a side elevation, partly in phantom, of a contact assembly embodying one form of my invention with the phantom view taken along the same plane as the cross sectional view shown in FIG. 2.

FIG. 2 is a side elevation, partly in cross section, of a high voltage conductor bushing embodying one form of my invention; shown with respect to the casing wall of a liquid filled transformer on which the bushing is mounted, and with respect to a manually movable conductor termination adapted to cooperate with the bushing.

FIGS. 3, 4, and 6 are fragmentary views of the operating components of the invention shown in FIG. 2, with these components depicted at various positions in their respective operating cycles.

Referring now to FIG. l of the drawing, there is shown a portion of the casing wall 1 of a distribution transformer of the type that is adapted for underground operation. A high voltage electrical conductor 2, shown in the form of a threaded copper terminal, is affixed in any suitable manner to the bottom of a metallic cylinder 3, which in turn is mounted coaxially in a high voltage epoxy bushing 4. In the preferred embodiment of my invention shown in FIGS. 1 and 2, the threaded terminal 2 comprises an integral part of the metallic cylinder 3 so that a separate manufacturing operation to connect these members is not required. In sealing the cylinder 3 to the bushing 4, I have found it desirable to cast the cylinder 3 into the bushing 4 at the time that it is molded into the required insulating configuration. This technique affords an hermetic seal between the cylinder 3 and the bushing 4. An annular groove 5 around the circumference of bushing 4 (see FIG. 2) seats the matching halves of a split mounting ring 6 and 6a which is sealed in the groove 5 with a suitable resin material 7. An annular gasket 8 is mounted on the recessed flange 9 of the casing Wall `1. In order to form an air-tight seal at the junction between the annular mounting ring 6-6a and the seating flange 9, a plurality of threaded bores 9a are provided at equally spaced points in the ange 9 and a plurality of bolts 10 are threaded into the bores 9a and rotated to compress the sealing gasket 8. When thus assembled in operating position on the wall of the transformer 1, the bushing 4 forms an hermetic seal between the inside and outside Wall 1 on the transformer.

Within the well defined by cylinder 3, there is disposed a slidable piston 11 comprising an annular aluminum channel having an elongated electrical contact 12 mounted thereon. The contact 12 is preferably formed of copper with the upper portion thereof, from the bottom of vertical slits 13 to the top of the contact 12, silver coated. In addition to the contact 12, an insulating cylinder 14, formed of pressed organic fiber, is mounted on the upper surface of the piston 11 by having the ears 11a on the piston crimped against the bottom end of the sleeve 14 to compress it against contact 12 to retain it in position. Although they cannot be seen in FIG. 2 it will be understood that there are a plurality of slits through the walls of contact 12, such as the longitudinal slits 13 extending from equally spaced points on the uppermost end of contact 12 to a point thereon adjacent the bottom of the slits 13 that are shown in FIG. 2. This slitted construction of the upper end of contact 12 causes it to be relatively flexible and the upper ends of the lingers thus formed on contact 12 are resiliently biased inward to the position shown in FIG. 2. The reason for this particular contact construction is to assure firm electrical conducting engagement With a second high voltage contact 15, which is mounted in a high voltage conductor termination 16, formed of epoxy or other suitable insulating material. The interior of termination 16 is hollowed to form cylindrically shaped well 16a adapted to receive the insulating sleeve 14 when the termination 16 and the bushing 4 are moved into juxtaposition to engage the lingers on contact 12 with the second contact 15. It will be understood that the contact 15 may be connected in a suitable voltage grading junc tion to a high voltage conductor, such as a sheathed coaxial power conductor of the type used in underground power distribution systems.

'On the end of contact 15, there is mounted an elongated block of gas evolving, arc quenching material 17, which cooperates with a cylinder of similar material 18` mounted on the upper portion of the inside wall of the insulating sleeve 14, to evolve arc quenching gas when an arc is formed between these components. The end of the contact 15 is crimped around an extension on the block 17 to secure it in position. The matin-g surfaces of conductor termination 16 and bushing 4 are formed, respectively, as a frusto-conical cone portion 16b and a complementary cup-shaped conical surface 4a, to provide a voltage grading seal between these surfaces 4a and 16b. A coating of resilient elastomeric material 19 is bonded by a suitable heat treating process to the frustoconical surface 16b of the termination 16. The elastomeric material 19 forms a resilient gasket to make a Watertight electrically insulated junction between the mating terminations 16 and bushing 4 when they are in their contact engaging position.

Although a good electrical contact is provided between the conductive side walls of cylinder 3 and piston 11 which of course is in electrical and mechanical contact with contact 12, there is provided a flexible pigtail-type conductor 20 secured by a bolt 21 to threaded boss 22 welded on the top surface of the floor of cylinder 3. The other end of pigtail 20 is electrically and mechanically connected to a threaded boss 23 on the inner surface of piston 11 by another bolt 24. Piston 11 is slidably mounted within the cylinder 3 and adapted to have a predetermined range of movement defined by its engagement with screw 21 at one extremity of the range of movement, and by its engagement at the other extremity of the range of movement with a restraining ring 25, which is resiliently mounted in an annular groove 3a near the uppermost end of the cylinder 3. It will be understood that ring 25 has a segment of its periphery removed and that the remaining portion of the ring is resiliently biased radially outward so that it can be compressed to reduce its diameter sufficiently to enable it to be inserted into groove 3a, where it is then retained by its outward radial bias. It will be apparent that other suitable means may be employed for limiting the range of movement of the piston 11 and its piston mounted contact 12 and such alternative means are within the scope of my invention.

From the foregoing discussion, it can be seen that when contact 15 in termination 16 is moved into enga-gement with contact 12, an electrical circuit is completed from the junction of the contacts 15 and 12 through the aluminum piston 11 and pigtail 20 to the high voltage conductor 2 that forms an integral part of the cylinder 3. In order to attain a fuller understanding of the unique operation of my invention, its mode of functioning during the course of a contact-closing cycle under energized conditions, will be described in detail.

In the operation of the invention, assuming that both the contact and the high voltage conductor 2 are connected in respective energized electric distribution circuits; and further assuming that these contacts are completely disengaged, the coupling operation is as follows: An operator manually moves the conductor termination 16, by use of a conventional hot stick or other suitable insulating means, toward engagement with the termination 4. In performing this operation, the operator will naturally have to select a predetermined direction of motion for effecting the coupling of the terminations such that the contact 15 is moved axially with respect to the contact 12. When this is done, the arc extinguishing block 17, affixed to the end of contact 15, will be inserted in the -cylindrical bore of the gas evolving cylinder 18. As the gas evolving block 17 engages the lingers on contact 12, these fingers grip the block 17 tightly enough to cause the piston 11 to be moved into contact with the bolt 21 as the movement of block 17 toward contact-closing position continues. This phase of the closing cycle is illustrated in FIG. 3 (assuming the normal forces of gravity had not already moved piston 11 to that position). Further manual movement of the termination 16 toward the bushing 4 brings the respective contacts 12 and 15 to the relative position shown in FIG. 4. At this point, a prestrike arc, illustrated in lFIG. 4 by the lines 26, is formed between the contact 12 and contact 15. This arc is confined between the arc quenching block 17 and the coaxially disposed gas evolving material 18 so that the arc is forced to play along the respective surfaces of these components and thereby causes a substantial amount of arc-snufiing gas to be developed. It will be seen that the hollow cylindrical sleeve 14 defines a gas confining passageway that extends longitudinally along the arc quenching block 17, through the slots 13 in contact 12, and thence through the hollow center of contact 12 into the bottom of cylinder 3. Since the bottom surface of piston 11 has a substantially greater area than the area exposed to the arc-generated gas by the upper surfaces of contact 12, the increasing gas pressure exerts a net upward thrust on the piston 11 which causes it to move rapidly toward the opposite extremity of its predetermined range of movement through the intermediate position shown in FIG. 2 to thereby bring the contact 12 quickly into electrical conducting engagement with the contact 15, as shown in FIG. 5, thus, snufling out the arc 26.

This automatic movement of the piston mounted contact 12 takes place without any further movement of the termination 16 and its associated contact 15 with respect to the bushing 4. The particular automatic feature of the closing operation of my invention has been found to be particularly advantageous in limiting the amount of contact damage resulting from unduly prolonged arcs during normal manual closing of contacts, such as those found in ordinary underground terminations. The advantages of this feature are even more apparent in instances where, due to a tendency on the part of unskilled operators to move energized contacts into engagment too slowly, the burning cycle of the arc is unduly prolonged, causing excessive damage to the respective terminals. Such damage is completely obviated by my invention, which removes the arcing portion of the closing cycle completely from control of the operator. It will be understood that in some applications where the line voltage is low, only a small arc may be developed on pre-strike, and such an arc may not develop enough gas to close contacts 12 and 15 before they are closed by manual pressure exerted by an operator. However, contact erosion in such application is usually not severe, and my invention assures prompt contact` closing if for any reason the operator fails to follow through rapidly with his contact closing movement because once an arc prestrikes gas starts to build up, and even with a small arc this build up is rapid enough to force the automatic closing of contacts 12 and 15 in a very limited amount of time. The contact closing operation is completed by further movement of the termination 16 toward bushing 4, to seat the surface 16b in sealing engagement of surface 4a, as shown in FIG. 6. It will be noted that this last portion of the operation also serves to move piston 11 back toward its lower extremity of movement adjacent the bolt 21. In the preferred embodiment of my invention, piston 11 is seated on the walls of cylinder well 3 with a loose enough fit so some of the gases in the cylinder can pass around the outer circumference of piston 11, while the remaining gases flow through the bore in contact 12 and the slits 13 at its upper end, when the piston 11 is moved toward contact with bolt 21. Of course, in some applications of the invention it may be desirable to provide additional pressure relief means to remove gas from the cylinder 3 as the final manual phase of engaging the termination 16 with bushing 4 is completed. For example, a small bore (not shown) may be provided through the piston 11 to afford a gas conduit between its upper and lower surfaces. Pressure relief means to attain such results are within the intended scope of my invention.

As the gases are forced out of the cylinder 3 by the continued movement of piston 11 toward bolt 21, they are largely exhausted from the space between bushing 4 and temination 16 before these members are sealed by seating of elastomeric material 19 on the surface 4a of bushing 4.

The operating cycle of my invention, which essentially eliminates arc erosion of the contacts, demonstrates that even during normal duty contact closing operations a major advantage is obtained; however, an even more important advantage derived from the invention is the added safety that it provides in the event a fault current condition exists on either portion of the circuit being connected prior to the time that contact is made. Should such a fault condition exist, for example, on the coaxial underground cable connected to contact 15, an extremely large arc 26 would be formed between the contacts 12 and 15 as they approach contact closing position. This arc would almost instantaneously develop a large amount of gas, which might explode the termination 16 or bushing 4, or it might throw the termination 16 back toward the operator. Either of such conditions could be hazardous to the operator and may well result in extensive and costly damage to the equipment. However, with my invention the amount of gas formed is maintained at a negligible level because as gas pressure builds up the rate of acceleration of piston 15 increases in direct proportion to such a build up; thus, the faster gas pressure mounts in the gas confining passageway defined by sleeve 14 and the bore of contact 12, the more rapidly the contact 12 is closed against contact 15 to extinguish the arc. Accordingly, regardless of the magnitude of arcing current, the duration of the arc and consequently the amount of gas it evolves is maintained at an extremely small level by the operation of my invention. Thus, the equipment and nearby personnel are always protected against explosive damage stemming from contact arcs.

A further desirable operating characteristic of my nvention is its ability to act as a quick-break contact opening means to again limit the duration of arcing and, thus, the amount of arc-generated gases formed within the confined contact enclosure. 'Ihe quick-break feature of the invention will be understood by considering the operation of my invention starting with the assumption that termination 16 is completely seated in bushing 4 with the Contact 15 firmly engaged by the fingers on contact 12. In this relative position of the operating parts of the invention, the piston 11 will be moved near the lower extremity of its predetermined range of movement dened by the bolt 21 limiting the downward movement of the piston 11, as shown in IFIG. 6. Now, as the termination 16 is manually withdrawn from the bushing 4 by an operator moving it with a hot stick or other suitable handling means, the contact 12 will remain firmly in engagement with contact l15 while the piston ,11 slides upward in the cylinder well 3. This relative position of the contacts 12 and 15 will be maintained by the friction between them until the upper surface of piston 11 contacts the piston retaining ring 25 and is, thus, restrained from further movement at the upper extremity of its predetermined range of movement, as shown in FIG. 5. At this point, the manual movement of termination 16y and its associated contact 15 has accelerated to a considerable momentum in a direction tending to separate the contacts 12 and 15; accordingly, when the contacts 12 and 15 now slide apart they do so rapidly, therefore, the arc 26 formed therebetween is quickly stretched to increase its resistance and thus speed its extinction. This arc stretching effect is further aided by the gas actuating means of my invention due to the fact that (as seen in FIG. when contacts 12 and 15 first separate, the arc quenching block 17 is in a position where it still is adjacent the slits l13 in contact 12. However, `gas generated by the arc 26 can enter the cylinder 3 but since contact 12 has reached its upper limit of movement and is stopped by ring 25, the increased pressure in cylinder 3 can only help to move the contact follower 17 and contact 15 upward, away from contact 12. Also, since the surface area on the upper end of contact 12 is slightly larger than the surface area on the bottom of arc quenching sleeve 1i8, a net upward thrust is exerted on the bottom surface of sleeve 1:8 forcing it to move rapidly away from the contact 12. This quick-break driving force is maintained until the piston 11 reaches the position shown in FIG. 4, where arc-generated gas flows freely through the slits 13. Due to the momentum of contact 15 and termination 16 away from bushing 4, coupled with the inertia imparted to contact 12 and piston 11 by the initial net downward thrust of gas on the upper surfaces of contact V12., the contacts 12 and 15 are completely separated before the direction of movement of contact 12 can be reversed; therefore, no restrike arc can be formed between the contacts. Accordingly, the net upward force of gas on the piston 11 near the end of the contact opening cycle only serves the desirable function of cushioning the impact of piston 11 on bolt 21.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention and, therefore, it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. lIn an electric circuit maker and breaker, a pair of elongated rod and bore contacts coaxially movable for telescopic engagement, a gas confining cylinder mounted adjacent said contacts to closely surround said contacts prior to their engagement with one another, a block of material which evolves arc extinguishing gas when contacted by an electric arc formed between said contacts, means mounting said block of material adjacent the end of at least one of said contacts so that it will be exposed to an arc formed between the contacts, and gas operated means responsive to increased pressure developed in the cylinder by said gas when the contacts are moved close enough together to cause an arc to prestrike them to move said contacts rapidly together to extinguish said arc.

engagement of said contacts when an electric arc is formed between them comprising a cylinder, a piston slidably mounted in said cylinder, said piston being connected to drive said contacts into engagement when said cylinder is filled with arc-generated gas, and means for channeling substantially all of the gas developed by an arc formed between said contacts into said cylinder thereby to fill the cylinder with said gas and rapidly increase the pressure applied by the gas to the side of said piston facing toward the cylinder while preventing any substantial increase in gas pressure on the side of said piston facing away from said cylinder thus causing said contacts to be driven rapidly into engagement.

5. A combination as defined in claim 4 wherein said means for channeling gas comprises a gas confining housing disposed around said contacts, and means defining a passageway between said housing and the interior of said cylinder.

16. A combination as defined in claim 4 wherein one of said contacts is mounted on said piston and the other contact is adapted to be manually moved into engagement with said piston-mounted contact.

7. A combination as defined in claim 6 including a high voltage coaxial cable provided with a voltage grading termination on one end thereof and connected at said one end to said manually movable contact, and further including a second voltage grading termination having a high voltage conductor coaxially disposed therein, said voltage grading terminations being adapted to be moved into engagement to form a voltage grading, water-tight seal therebetween when said contacts are moved into engagement, and means affording an electrical connection between said coaxial conductor and said piston-mounted contact wherein the gas confining housing around said contacts is sufficiently large to enable the respective terminations to remain in water tight sealed relationship during an arc extinguishing operation Iwithout venting arc generated gases from said housing.

8. A quick-break contact assembly comprising, in cornbination, a high voltage conductor, an insulating housing surrounding at least a portion of said conductor, means for movably mounting a contact adjacent said housing, means affording an electric current conducting connection between said movably mounted contact and said high voltage conductor, said movably mounted contact being adapted to engage a second contact that is moved tnto engagement therewith along a predetermined path, contact movement retaining means rigidly mounted at one extremity of said predetermined range of movement, said movably mounted contact being operable to be moved into engagement with said retaining means at one extremity of its range of movement when in engagement with said second contact, and being further adapted to maintain its engagement with said second contact through a predetermined portion of said range of movement when the second contact is moved along said predetermined path in a direction away from the movably mounted contact, whereby the second contact attains a substantial rate of acceleration and is maintained in engagement with the other contact before the contacts are separated by the movement of said second contact away from said movably mounted contact when the latter contact is stopped at the end of said predetermined range of movement, thereby affording a quick-break of the circuit formed by said contacts.

9. A quick-break contact assembly as defined in claim 8 wherein said means for movably mounting a contact adjacent said housing comprises a piston slidably mounted in a cylinder formed in said housing, and movably mounted contact being mounted on said piston for movement therewith.

`10. A quick-break contact assembly as defined in claim 9 wherein said insulating housing comprises a voltage grading termination for said conductor provided with means for forming a water-tight seal with a second termination adapted to house said second contact, whereby a voltage grading, water-tight connection is afforded around said contacts when they are in engagement and said movably mounted contact is moved toward said one extremity of its range of movement.

11. A high voltage electrical conductor termination comprising an elongated insulating housing having a frusto-conical surface formed in one end thereof with its maximum diameter adjacent said one end, a cylinder formed in said housing with one end thereof abutting the minimum diameter end of said frusto-conical surface; an electrical conductor extending coaxially through said housing from the other end of said cylinder to the other end of said housing, a piston slidably disposed within said cylinder, an electrical contact mounted on said piston adjacent said frusto-conical surface, means for conducting electric current from said conductor to said contact, a second electrical contact adapted to be moved into conducting relation with the contact on said piston, an insulating member for mounting said second contact having a frusto-conical surface complementary to the frustoconical surface of said housing and adapted to form a water-tight, voltage grading connection therewith when said first and second contacts are moved into juxtaposition, means defining a uid confining passageway extending from the generally enclosed volume of said cylinder beyond the outermost portion of the contact mounted on said piston, said passageway being operative to at least partially surround both of said contacts when they are moved within a predetermined distance of one another thereby to confine gas formed by an arc between said contacts in said passageway and channel the gas into said cylinder where it acts to drive the contact-carrying piston toward said second contact and rapidly close said contacts, the range of slidable movement of said piston mounted contact being adequate to allow the gas-actuated piston to close said contacts without requiring further movement of the second contact after an arc is formed between said contacts.

12. A high voltage conductor termination as defined in claim 11 wherein the means for conducting electric current from said conductor to said piston mounted contact comprises a fiexible electrical conductor connected between said coaxial conductor and said piston, and nclud ing means on said piston adapted to afford an electrical circuit between said flexible conductor and said piston mounted contact.

|13. A high voltage conductor termination as defined in claim 11 wherein said means detining a fluid confining passageway comprises a hollow cylinder mounted on said piston with its longitudinal axis extending outwardly therefrom to completely surround the piston mounted contact, and a bore through said piston providing a fluid conducting path between the cylinder in said housing and the hollow cylinder on said piston.

14. In a high voltage electrical conductor termination adapted to be mounted on an electrical device to provide a Voltage grading, water-tight electrical connection between operative components Within said device and a separate, high voltage electrical conductor, the combination comprising an electrical conductor extending through said termination, a gas-actuated cylinder and slidable piston arrangement disposed in said termination, an electrical contact mounted on said piston for movement therewith, a flexible electrical conductor connected to complete an electric circuit between said conductor and said contact, means defining a gas confining passageway through said contact, said passageway being in gas exchanging relationship with the interior of said cylinder and effective to confine substantially all of the arc-generated gas formed by an arc on said contact and direct said gas into the cylinder thereby to rapidly increase the pressure applied by the gas to the side of said piston facing toward the cylinder While preventing any substantial increase in gas pressure on the side of said piston facing away from said cylinder thus driving the piston toward one end of said cylinder, whereby the contact is rapidly moved in a predetermined direction by said piston when a gas generating arc is formed on said contact.

15. A combination as defined in claim 14 wherein said gas confining passageway is adapted to confine igas formed by an arc between said contact and said separate conductor and to direct said gas into said cylinder, said predetermined direction of movement of said contact being toward engagement with said separate conductor.

References Cited UNITED STATES PATENTS 1,955,215 4/'1934 Whitney et al ZOO-150.6 2,231,576 2/ 1941 Grosse ZOO-149.1 3,374,331 3/1968 Brockhaus et al. 200-51 X FOREIGN PATENTS 683,529 11/1939 Germany. 693,602 7/ 1940 Germany. 383,931 11/ 1932 Great Britain. 914,400 1/1963 `Great Britain.

ROBERT S. MACON, Primary Examiner U.S. Cl. X.R. 200-51, 148, 151 

